The present invention generally relates to controlling video playback systems, and more particularly, to a method and apparatus for communicating stop and pause commands for controlling viewing of moving pictures.
In recent years, systems for sending, storing and playing back video information and data from a wide selection of video sources have been developed. These have found widespread use among consumers. In addition to conventional video sources like digital video disks (DVD) and VCRs, video from other sources can be sent, stored and played back to a viewer at the viewer's convenience. Video sources include cable, satellite and broadcast television sources, as well as the Internet. One example of a commercially available storage and playback system is Personal Television (PTV). PTV refers to the viewing of live television programming in a manner that gives the viewer flexible viewing options, for example, pause and rewind. PTV is also known as Personalized TV, Personal TV Service, File-served Television, Time Delay Recording, Time Shifting and Individualized TV.
One of the video playback features highly desired by consumers is generally referred to in the art as “trick play”. The term “trick play” refers to using controls such as pause, instant replay, rewind etc. to control the video presentation. One reason this is referred to as “trick play” is because these operations can be performed while watching live TV in near real time. In order to implement such features, video signals (including live TV signals), are typically stored in a memory device, e.g., a hard drive, before being provided to a display unit for display to the consumer.
Another feature desired by consumers is the ability to stop the presentation of a show. The stop command differs from the pause command (also referred to as “freeze”). While both commands typically stop the presentation of moving pictures, the pause command results in display of a still video frame of the motion picture. The stop command stops the presentation but does not display a still video frame of the moving picture. Implementing both the stop and the pause features can be problematic for recording and playback systems. In most cases, the decoder in the display device is not under the control of the recorder and playback system. If the recorder/player stops sending frames in response to both the stop and pause commands, it is difficult for the decoder to distinguish between the stop and pause commands. Furthermore, for a pause command, the decoder is typically unable to determine how many times a particular picture will be displayed. This uncertainty interferes with the display order of the pictures being transferred to the display device.
Therefore, a need exists for improved systems and methods for implementing the STOP and PAUSE features for such devices.